Molded resealable closures have become the norm for packaging of many products. This is particularly true in the packaging of food products such as milk, juice and the like. These closures have also come into widespread use in the packaging of particulate and solid food stuffs such as soups, as well as non-food items such as laundry detergent.
One typical use for these closures is in conjunction with a paperboard container such as a gable top carton. In such an arrangement, the closure is mounted to a top gable panel of the carton. Typically, these closures include threaded or snap-type caps to seal the closure and the container contents from the environs.
In one typical application, the closure assembly includes an outer flange and a pour spout extending from a surface of the flange. The flange is mounted to the carton, by, for example, ultrasonic welding. A membrane or barrier is formed as part of the closure, internal to the pour spout, and extends thereacross. The membrane provides a seal prior to initial use of the container, as well as indication as to whether the container has been opened or the contents tampered with.
In various applications, the carton and its contents are sterilized to reduce product degradation by, for example, contaminants, such as bacteria and the like. This also serves to extend the "shelf-life" of these food products. To reduce the opportunity for bacterial growth, it has been found that it is most advantageous to position the membrane flush with the flange to eliminate any pockets or corners that may be conducive to such bacterial growth.
In order to maintain product preparation and packaging at a cost effective level, packaging machines have been developed to operate at greater and greater speeds, while maintaining high sterility standards. Many such machines perform the overall function of "form, fill and seal" to form the package, fill the package and seal the package within sterile processing environments. This operation also includes the step of mounting the closure to the carton or package.
In one known arrangement, the closure is carried by an anvil, which is commonly referred to as a "spud", into contact with the carton material and supported as the closure is mounted to the carton. The closure is typically mounted to the carton by ultrasonic welding and other known processes. Due to the nature of the high speed equipment and the mechanical forces such as vibration to which the closure may be subjected during welding, a variety of arrangements are used to maintain the closure secured to the spud during transport and welding.
To secure the closure to the spud, one known arrangement uses detents formed on the spud and the closure that engage one another to frictionally hold the closure. While this arrangement may be an effective method for securing the closure during transport and welding, it can have its drawbacks, as any frictionally engaging mechanical systems will, vis-a-vis tolerances, fit and the like.
In another known arrangement, a vacuum is applied to the closure membrane, through the body of the spud, to secure the closure in place. However, it has been observed that these systems that use a vacuum applied directly to the membrane, to support the closure, can result in an unacceptably high rate of closure failures. It is believed that one failure mechanism is due to the application of the vacuum applied directly to the membrane. Because the membrane is thin and is spaced upwardly from the flange into the spout, undue forces are exerted at about the membrane-spout juncture which can result in fracture of the material at about the membrane edge region.
Accordingly, there exists a need for an anvil or spud for engaging and supporting the closure as it is moved into position adjacent the package material and while it is secured to the package. Desirably, such a spud uses a vacuum to hold the closure thereto during transport and mounting to the package material. Most desirably, the vacuum is directed away from the membrane and is configured to reduce or eliminate undesired stresses and forces on the closure, and in particular the membrane, which forces and stresses can otherwise result in membrane and/or closure failure.